Gut forked, two suckers, the posterior sucker (acetabulum) ventral. It is always separated from the hind end by at least a part of the genitalia.
Family. Fasciolidæ, Railliet, 1895.
Large flat forms, genital pore in front of ventral sucker, the latter powerful. Vitellariæ of numerous follicles, united by branching vitellarian ducts, at the sides of the body meeting posteriorly and extending ventrally and dorsally. Cirrus and vagina without spines. No crown of strong spines around sucker. Testes much branched. Uterus not well developed. Excretory bladder much branched. Eggs large.
Sub-family. Fasciolinæ, Odhner, 1910.
Large or median forms, gut much branched. Body has a shoulder separating head from body. Receptaculum seminis absent. Ovary branched, ventral sucker in anterior part of body. Genus: Fasciola.
Sub-family. Fasciolopsinæ, Odhner, 1910.
Shoulder absent. Receptaculum seminis present. Ovary branched, gut takes a zig-zag course with kinks on it, ventral sucker in anterior part of body. Genus: Fasciolopsis.
Family. Opisthorchiidæ, Braun, 1901, emend. auctor.
Ovary in front of testes. Small to medium flukes, very transparent, tapering anteriorly. Vitellaria moderately developed not extending in front of sucker. Cirrus absent. Seminal vesicle a twisted tube free in parenchyma. Testes near hind end one behind the other, lobed or branched, but not dendritically. Excretory bladder Y-shaped, the two limbs short, the stem S-shaped passing between the testes. Receptaculum seminis well developed. Laurer’s canal present. Uterine coils transverse, numerous. Eggs small.